 |
| Titel |
Characterization of interactions between soil solid phase and soil solution in the initial ecosystem development phase |
| VerfasserIn |
Claudia Zimmermann, Wolfgang Schaaf |
| Konferenz |
EGU General Assembly 2010
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250041296
|
|
|
|
|
|
| Zusammenfassung |
| In the initial phase of soil formation interactions between solid and liquid phases and
processes like mineral weathering, formation of reactive surfaces and accumulation of
organic matter play a decisive role in developing soil properties.
As part of the Transregional Collaborative Research Centre (SFB/TRR 38) ‘Patterns and
processes of initial ecosystem development’ in an artificial catchment, these interactions are
studied at the catchment ‘Chicken Creek’ (Gerwin et al. 2009). To link the interactions
between soil solid phase and soil solution at the micro-scale with observed processes at the
catchment scale, microcosm experiments under controlled laboratory conditions were
carried out. Main objectives were to determine the transformation processes of C
and N from litter decomposition within the gaseous, liquid and solid phase, the
interaction with mineral surfaces and its role for the establishment of biogeochemical
cycles.
The microcosm experiments were established in a climate chamber at constant 10 Ë C. In
total 48 soil columns (diameter: 14.4 cm; height: 30 cm) were filled with two different
quaternary substrates (sand and loamy sand) representing the textural variation within the
catchment at a bulk density of 1.4-1.5 g*cm-3. The columns were automatically irrigated
four times a day with 6.6 ml each (corresponding to 600 mm*yr-1). The gaseous phase in the
headspace of the microcosms was analysed continuously for CO2 and N2O contents. C and N
transformation processes were studied using 13C and 15N labelled litter of two different plant
species occurring at the catchment (Lotus corniculatus, Calamagrostis epigejos) that was
incorporated into the microcosm surface. All treatments including a control ran with four
replicates over a period of 40 weeks. Two additional microcosms act as pure litter
controls where substrate was replaced by glass pearls. Litter and substrate were
analysed before and after the experiment. Percolate was continuously collected and
analyzed in two weeks intervals for C and N contents (including δ13C), pH and ion
concentrations.
The results show that the initial phase of the experiment is characterized by intensive
leaching of C and N from the litter and transformation as well as leaching from the
substrate. Calcium leaching is caused mainly by carbonate dissolution from the
substrates. In contrast, magnesium and especially potassium are leached in initially high
amounts from the litter, but are strongly retained in the soil. The addition of litter
promotes microbial CO2 production as shown by a strong increase of respiration due to
easily available organic substances at the beginning of the experiment. Litter of L.
corniculatus induced also a high initial peak in N2O emission as well as higher
nitrification and NO3-N leaching. Leaching of DOC and TDN was clearly affected by
the substrate texture, illustrated by intensive DOC leaching from the sand at the
beginning of the experiment but shifting later to higher leaching rates from the loamy
sand.
References:
Gerwin W, Schaaf W, Biemelt D, Fischer A, Winter S, Hüttl RF (2009) The artificial
catchment “Chicken Creek” (Lusatia, Germany) - a landscape laboratory for interdisciplinary
studies of initial ecosystem development. Ecolological Engineering 35, 1786-1796. |
|
|
|
|
|
|